Characteristics Of Soil Seed Bank And Its Relationship With Aboveground Vegetation In Dajiuhu Wetland

Dajiuhu is a special subalpine peat swamp wetland in Central China,which creates a good living environment for all kinds of organisms.However,in the process of social and economic development in modern times,the nature of the land use of the wetland has been constantly changing,resulting in the destruction of peat swamp resources due to over exploitation and use,the deterioration of wetland functions,and the sharp decline of biodiversity;Until 2005,after the protection and utilization of Dajiuhu wetland,the environmental situation was gradually improved.Dajiuhu wetland is not only special in nature,but also the largest tributary of Hanjiang The water intake point of the Middle Route Project of South to north water diversion is the birthplace of Duhe River,which has high water supply service value.Based on the dynamic changes of soil seed bank and aboveground vegetation in Dajiuhu wetland,this study analyzed the composition scale of soil seed bank,the composition of aboveground vegetation and the relationship between them,as well as the determination of soil total nitrogen and total phosphorus in the habitats where vegetation grows.It answered the contribution of soil seed bank to aboveground vegetation,and discussed the composition of wetland soil seed bank in different types of habitats In order to understand the direction and trend of vegetation succession in Dajiuhu wetland,evaluate the restoration status of wetland ecosystem in Dajiuhu since the implementation of water related project,and provide scientific basis for the protection of Wetland Park,it has special ecological significance and scientific research value to analyze the vegetation succession mechanism of wetland ecological environment,It can provide scientific decision-making basis for wetland protection and restoration of degraded wetlands.The results are as follows:1.According to the three physical and chemical properties of soil,the soil p H of Dajiuhu peat swamp wetland is slightly acidic;The maximum content of total nitrogen was 36.88 g / kg,the minimum was 6.65 g / kg,and the average was 16.59 g / kg;The maximum content of total phosphorus was 1.60 g / kg,the minimum was 0.01 g / kg,and the average was 0.89 g / kg.There was no significant difference in the contents of TN and TP in different soil depths,but TN was mainly distributed in the surface soil.There was no significant difference in the content of total nitrogen and total phosphorus between different zones.The average value showed that the content of total nitrogen in W was the highest and that in E was the lowest,while that in M was the highest and that in E was the lowest.2.The germination experiment of soil seed bank shows that there are 35 species of germination in Dajiuhu wetland,belonging to 16 families and 26 genera.The average germination density of seeds is 3112 ± 742.5 grains / M 2? From the perspective of life form,the annual herbaceous species accounted for the largest proportion,and the perennial plants had the largest number of seeds and the largest density,1853.5 seeds /m 2.The species of sargassaceae are the most,including 7 species,followed by Gramineae.The frequency of occurrence of Cordyceps was 85% and the average density was 1853.5 grains / m 2,The dominant species in seed bank is Cordyceps.The vertical distribution of soil seed bank is analyzed.The number of species germinated in seed bank changes with the depth of soil layer,that is,the number of seeds germination in surface soil is the most,and the less the germination quantity is with the deepening of soil depth.3.The results of the above ground vegetation survey show that there are 131 species of vegetation in Dajiuhu wetland,belonging to 39 families and 101 genera.In terms of life form,perennial herbs accounted for 64.88%,followed by annual plants21.37%.Among them,Compositae is the largest family with 17 species,accounting for12.98%.The dominant species were Polygonum Sagittarius,Trifolium pratense and sinocalyx chinensis.4.The Shanon-Wiener index and Simpson diversity index of aboveground vegetation were higher than those of soil seed bank,margale richness index was higher than that of soil seed bank,but Pielou evenness index of soil seed bank was higher than that of aboveground vegetation.The two similarity coefficients of soil seed bank and aboveground vegetation are small,indicating that the number of the same species is not much,and the contribution of soil seed bank to aboveground vegetation is small.The dominant species in aboveground vegetation were Polygonum Sagittarius,Trifolium pratense,Prunus chinensis and Sanguisorba officinalis,while the dominant species in seed bank were rush,Poa pratensis,pseudorice and Scirpus triqueter.The above ground vegetation was dominated by perennial plants,and the annual biological species accounted for the largest proportion in the seed bank.5.The change of soil seed bank under different water content showed that with the distance from the lake to the dry meadow,the soil seed bank had the highest number of germination and the highest richness in the transition area when the soil water content was less,and the species diversity of aboveground vegetation was the highest when the water content was the least,The evenness index is the highest and the species richness index is also the highest.The species diversity index of soil seed bank was lower than that of aboveground vegetation,and the similarity index of them was lower,and the similarity index in the transition zone was the highest,which indicated that the soil seed bank was the most suitable for the growth and reproduction of hygrophytes under moderate water conditions.6.The comparison of aboveground vegetation in the three periods,compared with the survey data of the former in 2012,increased 36 species.Compared with the survey data of the former in 2006,there are 282 species less,and the increased species are mainly arbor and shrub woody plants and herbaceous plants growing under the forest.From the overall comparison of the three periods,the vegetation diversity of Dajiu Lake wetland has increased,which indicates that since the implementation of a series of ecological environment protection projects such as returning farmland to grassland and forest,Lake reconstruction,etc,The ecological environment of wetland has been improved.